1. Field of the Invention
The present invention relates to pressure sensitive adhesive compositions suitable for various medical applications and especially suitable for use for adhesion to the skin, in particular in the field of ostomy care. More specifically, this invention relates to adhesive compositions comprising a rubbery elastomeric base and one or more water soluble or water swellable hydrocolloids dispersed therein, the use of such adhesive compositions for the preparation of a wound dressing or an adhesive wafer for an ostomy appliance, and to wound dressings or ostomy appliances comprising such adhesive composition.
In connection with surgery for a number of diseases in the gastro-intestinal tract a consequence is, in many cases, that the colon, the ileum or the urethra has been exposed surgically and the patient is left with an abdominal stoma and the effluents or waste products of the body, which are conveyed through these organs, are discharged through the artificial orifice or opening and are collected in a collection bag, which is usually adhered to the skin by means of an adhesive wafer or plate having an inlet opening for accommodating the stoma. Also in connection with a fistula, the patient will have to rely on an appliance to collect the bodily material emerging from such opening.
2. Description of the Related Art
Various skin adhesive agents are used today for the above mentioned purposes.
Such adhesives should have a composition which is sufficiently tacky to secure the appliance or skin barrier to the abdomen, and a cohesion ensuring safe removal thereof without leaving residues on the skin. Furthermore, the adhesive should show a degree of elasticity to enable the adhesive layer of the appliance or barrier to follow the movements of the patient without slipping the skin and should also show a great resistance to erosion caused by aggressive exudates from an ostomy in order to minimise the risk of leakage.
A very widespread embodiment of skin adhesive agents comprises a self-adhesive elastomeric matrix, in which water-absorbing, swelling particles, the so-called hydrocolloids, are dispersed.
Adhesive compositions comprising hydrocolloids have been known for many years. U.S. Pat. No. 3,339,549 discloses a blend of a rubbery elastomer such as polyisobutylene and one or more water soluble or water swellable hydrocol-loids such as a powdery mixture of pectin, gelatine and carboxymethylcellulose. The adhesive mass has a water-insoluble film applied to one surface. A composition of this type is available commercially from E.R. Squibb and Sons Inc. under the trademark xe2x80x9cStomahesivexe2x80x9d and is used as a skin barrier around stomas to prevent skin breakdown by the corrosive fluids discharged by the stoma.
In adhesive compositions of this type, the polyisobutylene is responsible for provision of the adhesive properties and the dispersed hydrocolloid powders absorb fluid and render the adhesive agent capable of also adhering to moist skin (wet tack). These compositions are also gaining increasing acceptance as wound dressings for dermal ulcers, bums and other exuding wounds. One major problem which has been encountered with conventional adhesive compositions comprising hydrocolloids is their susceptibility to breakdown upon exposure to body fluids. When the compositions are used as skin barriers, e.g., around stomas, absorption of fluid is desirable, but excessive swelling causes the composition to lose its integrity opening for leaks and the barrier must be replaced more often than is desirable from a skin protection point of view, and very often, a residue remains on the skin, which in many cases is difficulty to remove.
A number of attempts have been made to improve the properties of adhesive compositions in order to overcome the above-mentioned drawbacks.
U.S. Pat. Nos. 4,192,785 and 4,551,490 describe incorporating into an adhesive composition of a cohesive strengthening agent such as a natural or synthetic fibrous material, finely divided cellulose, cross-linked dextran, cross-linked carboxymethylcellulose or a starch-acrylonitrile graft copolymer. The cohesive strengthening agent is stated to control the rate of hydration of the composition thereby increasing the resistance against breakdown by body fluids.
U.S. Pat. No. 4,477,325 describes incorporation of a mixture of a copolymer resin of ethylene and vinyl acetate (EVA) into the adhesive composition. After mixing and moulding, the composition is subjected to ionising radiation to form a cross-linked polymer network of the EVA or comprising EVA and another cross-linked resin. The cross-linked matrix is said to provide a controlled swelling.
U.S. Pat. No. 4,496,357 describes the incorporation of fumed silica into adhesive compositions to control swelling.
EP Patent No. 0 122 344 B1 describes incorporation of one or more natural or synthetic polymers capable of developing elastomeric properties when hydrated, such as gluten and long chain polymers of methyl vinyl ether/maleic acid, into the adhesive composition. The adhesive composition is stated to be resistant to erosion by moisture and body fluids.
EP Patent No. 0 340 945 B1 describes incorporation of some polycationic hydrocolloid particles into a hydrocolloid composition. The mixture of polycationic, polyanionic and neutral hydrocolloids is stated to provide increased integrity without a concomitant decrease in absorbing capacity.
In other embodiments, styrene copolymers have been incorporated which is disclosed in a number of patent references.
In U.S. Pat. No. 4,231,369, Sorensen et al. disclose an ostomy skin barrier consisting of a physically cross-linked styrene copolymer having dispersed therein a water soluble hydrocolloid gum, a tackifier and optionally an oil extender.
In U.S. Pat. No. 4,367,732, Poulsen et al. disclose an ostomy skin barrier consisting of a water soluble hydrocolloid dispersed in a continuous phase consisting of a physically cross-linked elastomer, a hydrocarbon tackifier, and a plasticizer, an antioxidant, and optionally an oily extender.
U.S. Pat. No. 4,427,737 (Cilento et al.) discloses a breathable tape having a porous backing and a microporous adhesive layer comprising from about 30% to about 60% by weight rubbery elastomer selected from the group consisting of natural rubber, polyurethane rubber, and polyisobutylene, from 20% to about 65% by weight of one or more water soluble or water swellable hydrocolloids and up to 35% by weight of one or more tackifiers, plasticizers, antioxidants and preservatives.
In U.S. Pat. No. 5,633,010, Chen discloses a hydrocolloid composition comprising a unsaturated aliphatic homopolymer (20-50%) cross-linked by gamma radiation, a compatible tackifier (20-60%) and at least one hydrocolloid absorbent (5-60%).
U.S. Pat. No. 5,006,401 (Frank) discloses a composite compression dressing comprising 5-30% by weight of one or more polyisobutylenes or a blend of one or more polyisobutylenes and butyl rubber, from 3 to 30% by weight of one or more styrene radial or block copolymers, from 8 to about 40% by weight mineral oil and from 15 to 65% by weight of one or more water soluble hydrocolloid gums and up to 15% by weight of one or more water swellable cohesive strengthening agents, from 7.5 to 15% by weight of a tackifier and up to about 5% by weight of optional ingredients.
U.S. Pat. No. 4,551,490 (Doyle et al.) discloses medical grade pressure sensitive adhesive compositions comprising a homogeneous mixture of 5-30% of one or more polyisobutylenes, 3-20% of one or more styrene radial or block type copolymers, mineral oil, one or more water soluble hydrocolloid gums, and a tackifier. One or more water swellable cohesive strengthening agents, an antioxidant, and various other optional ingredients also may be included within the adhesive composition.
EP Patent publication No. 81907 discloses an ostomy appliance comprising a skin barrier (A) surrounding the stoma and a coupling element (B) including an outwardly extending flange permanently affixed to the skin barrier (A) and a microporous adhesive layer (C) having an upper porous layer. The skin barrier adhesive (A) comprises a homogeneous 30-70% of a blend of low molecular weight polyisobutylene and one or more optional thermoplastic elastomers selected from medium molecular weight polyisobutylene, butyl rubber, and styrene isoprene copolymers and having dispersed therein 35-65% of one or more water soluble hydrocolloids and one or more water swellable or inert cohesive strengthening agents.
Generally speaking, these prior methods are superior to improve the integrity of adhesive compositions. Nevertheless, need still exists for better adhesive composition having resistance to biological fluids as well as the properties of improved adhesion to the skin and strechability.
Now it has been found that an improved adhesive composition having resistance to biological fluids as well as the properties of improved adhesion to the skin and strechability may be obtained.
The present invention relates to a pressure sensitive adhesive composition suitable for various medical applications and especially suitable for use for adhesion to the skin, in particular in the field of ostomy care. More specifically, this invention relates to adhesive compositions comprising a rubbery elastomeric base and one or more water soluble or water swellable hydrocolloids dispersed therein, ostomy appliances comprising such adhesive compositions and the use of such adhesive compositions for preparing wound dressings or ostomy appliances.